Conventionally known is a building structure including a unit installed on a horizontal member. For example, Patent Literature 1 described below discloses such a building structure and has the following problem.
A building structure described in Patent Literature 1 (hereinbelow referred to as “a conventional technique”) has a configuration in which a unitary-structured wall girder connecting upper ends of pillars erected in a longitudinal direction is used as a horizontal member, and in which a unit is installed on this wall girder, and the wall girder is thus required to have high bending strength. For this reason, in such a building structure, heavy gauge steel such as H-shaped steel and I-shaped steel is used as the horizontal member. However, since this horizontal member is heavy, it is not easy to install the horizontal member on the pillars. Also, using the heavy gauge steel causes not only a problem of increasing the weight of the building but also a problem of increasing the material cost.
In the conventional technique, since the unitary-structured wall girder is connected to the pillars by means of pin joint, braces are required between the pillars erected in the longitudinal direction. On the other hand, in a case in which a glass wall is used as a wall material to be installed in the longitudinal direction, there is a demand for eliminating the braces. However, in the building structure requiring the braces, such a demand cannot be met.
In the conventional technique, the unit includes 1) a rectangular horizontal frame including a short side member, 2) a truss-structured beam connected to a center of the short side member in a lengthwise direction to be perpendicular to the horizontal frame, 3) a first diagonal member installed between one end of the short side member and the beam, and 4) a second diagonal member installed between the other end of the short side member and the beam. However, since this unit is installed on the horizontal member (wall girder) in a state in which the horizontal frame and the beam stand upright in an inverted T shape, the horizontal frame and the horizontal member overlap with each other, which is structurally inefficient.